A variety of systems have been developed for heating vehicle passenger compartments. Several of these previous systems relied upon a method of drawing heat from engine coolant fluid to provide heat to a vehicle passenger compartment. The coolant fluid flows through a heat exchanger where the heat of the fluid is transferred to the air flowing toward the passenger compartment. Once the coolant fluid passes through the heat exchanger, it is returned to the engine for recirculation. Because heat from the engine operation is responsible for heating the coolant fluid, and due to the inherent properties of coolant fluids, these systems often take a substantial amount of time to provide heat to passenger compartments after a cold start. Further, because these heating systems draw heat from an additional fluid, as opposed to harnessing heat from an existing engine fluid, engines utilizing these heating systems must contain an additional pump and plumbing. While these systems have performed well, there is room for improvement.
The present invention is directed to overcoming one or more of the problems set forth above and to improving the performance of passenger compartment heating systems.